Energization of the external running lights of a vehicle during ignition activation and engine operation is a safety measure. In some countries, it is the law that all new vehicles automatically have their headlights on while the ignition is on, and it would appear that the general trend of Government regulations in many countries will be to require daytime running light systems on automotive vehicles, both trucks and cars, and while certain Government regulations are presently addressed to newly manufactured vehicles, the possibility of retrofitting vehicles already in services is a consideration in the implementation of a daytime running light circuit system.
Studies have shown that the number of motor vehicle accidents can be substantially lowered if vehicles have their headlights and parking lights illuminated whenever the vehicles are operated, and in the future, insurance companies may require implementation of a daytime running light system for all insured motor vehicles.
Systems for causing activation of the external running lights while the ignition is turned on and the vehicle engine is running have been known in the prior art. For example, Haag et al. U.S. Pat. No. 4,684,819 discloses that the high beam headlights are energized at a reduced intensity in response to a predetermined vehicle operating condition. Kataoka et al. U.S. Pat. No. 4,899,083 discloses a bypass circuit bypassing a manual lighting switch, and during operation in an automatic lighting mode, the head lamps and a clearance lamp of the automobile automatically turn on when the engine operation becomes stable upon completion of start-up operation by the provision of a delay circuit which is used to open or close the bypass circuit. Eydt U.S. Pat. No. 4,686,423 provides an automotive headlight control including means to detect when the automobile engine is operating and cause the headlights to be operated at reduced output. Heintzberger et al. U.S. Pat. No. 4,831,310 provides an automatic headlight control system for causing the headlights of a motor vehicle to be actuated when the vehicle is running based on comparing an AC signal from the alternator to the DC signal from the battery and actuating the lights at a predetermined value. Papillon U.S. Pat. No. 4,667,129 discloses a method and device for automatically switching on and off the headlights of a motor vehicle, which takes into consideration the amplitude of the direct current voltage between the positive and negative terminals of the vehicle's battery, for the purpose of protecting both the battery and the headlights.
None of the above-identified prior art systems for automatically turning on and off the headlights and external running lights of a motor vehicle provide a high level of reliability and fail-safe operation, which is accomplished by the present invention.
Consequently, the need exists for improvements in automatic vehicle lighting systems which will result in greater reliability and safety, and to insure fail-safe operation.